From ab78029ecc347debbd737f06688d788bd9d60c1d Mon Sep 17 00:00:00 2001 From: Linus Walleij Date: Tue, 22 Jan 2013 10:56:14 -0700 Subject: drivers/pinctrl: grab default handles from device core This makes the device core auto-grab the pinctrl handle and set the "default" (PINCTRL_STATE_DEFAULT) state for every device that is present in the device model right before probe. This will account for the lion's share of embedded silicon devcies. A modification of the semantics for pinctrl_get() is also done: previously if the pinctrl handle for a certain device was already taken, the pinctrl core would return an error. Now, since the core may have already default-grabbed the handle and set its state to "default", if the handle was already taken, this will be disregarded and the located, previously instanitated handle will be returned to the caller. This way all code in drivers explicitly requesting their pinctrl handlers will still be functional, and drivers that want to explicitly retrieve and switch their handles can still do that. But if the desired functionality is just boilerplate of this type in the probe() function: struct pinctrl *p; p = devm_pinctrl_get_select_default(&dev); if (IS_ERR(p)) { if (PTR_ERR(p) == -EPROBE_DEFER) return -EPROBE_DEFER; dev_warn(&dev, "no pinctrl handle\n"); } The discussion began with the addition of such boilerplate to the omap4 keypad driver: http://marc.info/?l=linux-input&m=135091157719300&w=2 A previous approach using notifiers was discussed: http://marc.info/?l=linux-kernel&m=135263661110528&w=2 This failed because it could not handle deferred probes. This patch alone does not solve the entire dilemma faced: whether code should be distributed into the drivers or if it should be centralized to e.g. a PM domain. But it solves the immediate issue of the addition of boilerplate to a lot of drivers that just want to grab the default state. As mentioned, they can later explicitly retrieve the handle and set different states, and this could as well be done by e.g. PM domains as it is only related to a certain struct device * pointer. ChangeLog v4->v5 (Stephen): - Simplified the devicecore grab code. - Deleted a piece of documentation recommending that pins be mapped to a device rather than hogged. ChangeLog v3->v4 (Linus): - Drop overzealous NULL checks. - Move kref initialization to pinctrl_create(). - Seeking Tested-by from Stephen Warren so we do not disturb the Tegra platform. - Seeking ACK on this from Greg (and others who like it) so I can merge it through the pinctrl subsystem. ChangeLog v2->v3 (Linus): - Abstain from using IS_ERR_OR_NULL() in the driver core, Russell recently sent a patch to remove it. Handle the NULL case explicitly even though it's a bogus case. - Make sure we handle probe deferral correctly in the device core file. devm_kfree() the container on error so we don't waste memory for devices without pinctrl handles. - Introduce reference counting into the pinctrl core using so that we don't release pinctrl handles that have been obtained for two or more places. ChangeLog v1->v2 (Linus): - Only store a pointer in the device struct, and only allocate this if it's really used by the device. Cc: Felipe Balbi Cc: Benoit Cousson Cc: Dmitry Torokhov Cc: Thomas Petazzoni Cc: Mitch Bradley Cc: Ulf Hansson Cc: Rafael J. Wysocki Cc: Jean-Christophe PLAGNIOL-VILLARD Cc: Rickard Andersson Cc: Russell King Reviewed-by: Mark Brown Acked-by: Greg Kroah-Hartman Signed-off-by: Linus Walleij [swarren: fixed and simplified error-handling in pinctrl_bind_pins(), to correctly handle deferred probe. Removed admonition from docs not to use pinctrl hogs for devices] Signed-off-by: Stephen Warren Signed-off-by: Linus Walleij --- drivers/pinctrl/core.h | 3 +++ 1 file changed, 3 insertions(+) (limited to 'drivers/pinctrl/core.h') diff --git a/drivers/pinctrl/core.h b/drivers/pinctrl/core.h index 232a9f6db4aa..fdd350d639f6 100644 --- a/drivers/pinctrl/core.h +++ b/drivers/pinctrl/core.h @@ -9,6 +9,7 @@ * License terms: GNU General Public License (GPL) version 2 */ +#include #include #include #include @@ -58,6 +59,7 @@ struct pinctrl_dev { * @state: the current state * @dt_maps: the mapping table chunks dynamically parsed from device tree for * this device, if any + * @users: reference count */ struct pinctrl { struct list_head node; @@ -65,6 +67,7 @@ struct pinctrl { struct list_head states; struct pinctrl_state *state; struct list_head dt_maps; + struct kref users; }; /** -- cgit v1.2.3